In vitro and ex vivo permeation studies of chlorpheniramine maleate gels prepared by carbomer derivatives.

The antihistaminic chlorpheniramine maleate (CPM) is used for symptomatic relief of hypersensitivity reactions and in pruritic skin disorders. At present, the drug is marketed in tablet, capsule, syrup, cream, and injectable dosage forms. Chlorpheniramine maleate has some side effects when taken orally. Due to its first pass effect, only 25%-45% of the orally administered dose reaches the blood circulation. To bypass these disadvantages, we aimed to investigate percutaneous absorption of CPM from gel formulations prepared with different carbomer derivatives (Carbopol 934, 940, 941, 2984, 980, and 981; main differences are related to presence of a comonomer and cross-link density). Cellulose membrane was used as the diffusion barrier for all the formulations' drug-release studies. The release of active substance from carbopol derivatives, which have the least cross-linking density (Carbopol 941 and 981) was found to be numerically higher than the others. The formulation (F8; 1% Carbopol 941) that exhibited the maximum drug release through the cellulose membrane was further studied for drug release by using polyurethane membrane, excised rat skin, and human skin. The penetration of the active substance through different diffusion barriers was found to be statistically different (p<0.05) when compared. Of all the different diffusion barriers, rat skin gave the closest results to human skin. Thus topical application of CPM in the carbomer gel may be of potential use for local activity. The type and concentration of carbomers can affect drug release. The synthetic membranes are useful in assessments of formulations in quality assurance but they do not give definite indication of how a formulation will behave when it is used on skin.